Preadolescent depression is often a 'gateway' condition that increases the risk for recurrent depression into adolescence and adulthood. Early psychosocial interventions with depressed preadolescents are necessary to address interpersonal impairment that often increases their experience of stressful relationships and subsequent depression. The purpose of this Mentored Patient-Oriented Research Career Development Award (K23) is to acquire expertise necessary to develop and evaluate a family-based psychosoical treatment for preadolescent depression to decrease recurrent depression in adolescence. The candidate's long-term goals are to become an independent clinical interventions researcher, able to modify and evaluate family-based treatments for depressed children and preadolescents in diverse clinical settings. To achieve this goal, instruction and mentoring are proposed in three main areas: 1) development and evaluation of clinical interventions for depressed preadolescents, 2) transactional models and methods for assessing behavior dependent life events, and 3) statistical methods for longitudinal data. The research plan for this award is divided into two phases that will be implemented with the support of the training plan and team of mentors and consultants. First, a developmentally-appropriate, empirically informed psychosocial treatment protocol for Family Based Interpersonal Psychotherapy (IPT) will be developed and modified based upon the protocol's feasibility and acceptability in an open treatment trial with depressed preadolescents and their parents (n = 5). Second, a preliminary randomized controlled trial (RCT) will be conducted to assess the feasibility and acceptability of Family Based IPT (n = 30) and a control treatment, supportive nondirective treatment (SNDT, n = 15), in reducing preadolescents' depressive symptoms and improving interpersonal and family functioning across the course of treatment and at 3- and 6-months post-treatment. Exploratory analyses will investigate comorbid anxiety and current parental depression as correlates of treatment outcomes in the Family Based IPT condition: Data from these research activities will inform an R01 application for conducting a large controlled efficacy trial of Family Based IPT.